This invention relates to a device for contactless energy and data transmission, comprising a storage circuit with an output lead for the output of stored data, a coil for receiving a magnetic alternating field and for generating an alternating voltage, a circuit arrangement for generating a supply voltage for the storage circuit, the circuit arrangement comprising a rectifier circuit which is connected to the coil in order to generate the supply voltage from the alternating voltage, and a load device for generating an increased load of the coil which is dependent on the data to be output.
A device of this kind is known from DE-PS 32 42 551. The variation of the coil load influences the magnetic alternating field transmitted by a read station which cooperates with the storage circuit, and the variation of the magnetic alternating field can be detected in the read station so that the data from the storage circuit can be taken up in a contactless manner by the read station. Control of the storage circuit requires additional logic and control circuits which are combined with the storage circuit. Therefore, storage circuit is understood to mean hereinafter the combination including these additionally required circuits.
The evaluation of the variation of the magnetic alternating field due to the data-dependent load variation is more reliable as the coupling between the coil and the transmission device of the read station is stronger, and also as the load variation by the data is greater. Because the coupling may not be arbitrarily tight for mechanical and practical reasons, an as large as possible load variation should be induced by the data. Because the supply voltage for the storage circuit is derived from the coil, the coil is already loaded to a given extent thereby and because, on the other hand, in the case of excessive loading of the coil the supply voltage generated by the rectifier becomes too small, in the known device the extent of the permissible load variation is limited.